When upgrading to higher version, sometime the file location doesn't map properly (like older location removed). So as an advice, try to use different path rather than using default for your customized templates, weldment profiles, table templates, etc.

For this error, the path for Properties.text file is mapped to a location which doesn't have it or folder doesn't exist. Search for Properties.text file and map the path correctly under Tools > Options > File Locations > Custom Property Files

Followed your advice and indeed showed it was pointing to an old 2014 file path. I deleted that & that seems to have resolved. Just a correction on my part for completeness, what triggered the popup was right clicking a feature in the tree in order to define configurations.Thanks for the fast reply Deepak.